| In order to investigate the dynamics of the number of bacterioplankton, Vibrio, bacterial communities and the environmental factors including temperature, dissolved oxygen, potential of hydrogen, salinity, the redox potential, nitrite, nitrate, ammonium, and phosphate in aquaculture water or digestive tract of Haliotis discus hannai in Huilai Guangdong, fluorescence microscopy method, cultivation method and Roche GS FLX System were used. The interaction relationship between bacteria and environmental factors were analyzed for providing reference to predict the possible changes of bacterial communities the along with the change of environmental factors, healthful aquaculture, disease protection and prevention. This study started from March 2013 to February 2014. The main results were as follows:1. The detection results of environmental factors in aquaculture water were as followsDuring the monitoring period, water temperature variation range was 16.8~29.0 ℃(average 22.97 ℃), dissolved oxygen was 5.28~8.40 mg/L(average 6.83 mg/L), p H was 7.98~8.52(average8.31), salinity was 30.68~33.34(average31.98), and the redox potential was 7.50~100.09 mv(average58.99mv). Nitrite, nitrate, ammonium, and phosphate variation range respectively were 21.45~66.50 μg/L 、 42.60~157.40 μg/L 、23.75~135.83 μg/L、9.82~25.25 μg/L; and the average are 29.79μg/L、88.96μg/L、62.52μg/L、19.07μg/L。2. The detection results of aquatic Vibrio number and total bacteria number were as followsThe logarithm values of Vibrio quantity in aquaculture water throughout the year varied from 1.2 to 3.8(average2.9). In February and October the number of vibrio was significantly higher than other months(P<0.05), while in April the number of vibrio significantly lower than other months(P<0.05), and there was no significant difference among other months. When temperature was higher than 25℃, the number of vibrio was significantly correlated with temperature(P<0.01), redox potential(P<0.01), nitrate(P<0.05). When temperature was lower than or equal to 25℃, the number of vibrio had no correlation with any environmental factor. The logarithm values of bacterioplankton quantity throughout the year varied from 5.46to5.90,(average5.7). In August bacterioplankton quantity was the highest throughout the year and had a significantly difference with other months(P<0.05), and the January’s was the lowest throughout the year and had a significantly difference with next months(P<0.05).3. Results of the number of bacteria in the digestive tract of abalone were as followsThe logarithm values of Vibrio number in digestive tract of abalone throughout the year varied from4.02 to 6.41(average5.55), the highest was in May and the lowest was in June. The Vibrio number in June had no significant difference with January or February, while had significant difference with other months. When the water temperature was higher than 25 ℃, Vibrio number in digestive tract of abalone had significant correlation with dissolved oxygen, salinity, ammonium and the redox potential(P<0.05). When temperature was lower than or equal to 25℃, Vibrio quantity in digestive tract of abalone had significant correlation with Vibrio quantity in aquaculture, dissolved oxygen, the redox potential, potential of hydrogen, nitrate, ammonium(P < 0.01), and temperature, nitrite, phosphate(P<0.05).4. The analysis of bacterial communities in aquaculture water were as followsbacterial diversity index in aquaculture water was higher in May, June, July, August, and was lower in March, April, September, October, November, while the highest was in May and the lowest was in April. Dominant bacterial phyla in aquaculture water were: Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria, Planctomycetes. Bacteroidetes was the dominant bacterial phyla in July, Proteobacteria was the dominant bacterial phyla in the other months. The result of canonical correspondence analysis between bacterial communities and environmental factors in aquaculture water showed: bacterial diversity index in May had significant correlation with temperature, mineral nitrogen, salinity, potential of hydrogen; bacterial diversity index had significant correlation with potential of hydrogen in March, October, November; bacterial diversity index had significant correlation with potential of hydrogen in September. Bacterial diversity index had significant correlation with temperature and mineral nitrogen in June, July and August. Correlation between environmental factors and aquaculture water bacteria diversity index was: dissolved oxygen> mineral nitrogen>Temperature> salinity> the redox potential> potential of hydrogen. Therefore, dissolved oxygen and the mineral nitrogen were the main factors influencing the variation in bacterial diversity. |
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